FR2532699A1 - DEVICE FOR REDUCING THE AXIAL END GAP OF THE ARMATURE SHAFT OF A MOTOR - Google Patents

Abstract

A DEVICE FOR REDUCING THE END CLEARANCE OF ARMOR SHAFT 12 OF A DYNAMO-ELECTRIC MACHINE 10 INCLUDES A SHEET 22 OF ELASTIC MATERIAL WHICH IS KEPT IN PLACE ON THE HOUSING 11 OF THE MACHINE ONLY BY ITS EDGES ADJACENT TO ONE END OF THE ARMBRIDGE SHAFT. A HARDENED THRUST BEARING BODY 25 IS SUPPORTED BY THE STOPPER SHEET AGAINST THE END OF THE ARMBER SHAFT. THE SHEET OF ELASTIC MATERIAL PRESENTS UNDER TENSION A LOW TRANSMISSIBILITY OF NOISE, IN ORDER TO REDUCE THE TRANSMITTED NOISE, FROM THE ARMCHAIR OR THE STOPPER TOWARDS THE MACHINE STATOR, AND THEREFORE ITS SPREAD IN THE ENVIRONMENT.

Description

The present invention relates to a play reduction device

  axial end of the shaft d B induced by a motor. The armature shafts of electric motors are sometimes subjected to axial forces which can cause them to move forwards and backwards, noisily, between stops provided on the casing of the

  motor, unless the shafts are retained in place

  or another For example, in a wiper motor

  windows, such axial displacement is often caused by the reversal of the load when the wiper blade

changes scanning direction.

  Among the various means for reducing the axial play of endness of such motor armature shafts, it is known to include a thrust bearing in which

  a boss in a support material or bearing satisfactorily

  sant, or a steel ball, is pressed into the end

  of the shaft to lean against a stop plate cons-

  made of a compatible support material Other proposals

  The prior art includes devices which are made somewhat elastic to compensate for any axial end play, such as the elastic extended arms of the sheet metal plates of the structure shown in US-A-2,030,193 ( Arnold) Sometimes, as shown in US-A-3,549,218 (Cagnon et a 16), a plate

  hardened, or some other form of stopper, is direct-

  supported by the motor housing.

  However, it is not only desirable that the device used to make up the end play of a motor armature shaft have high bearing qualities. In many applications, it is also desirable that the device minimize the transmission of audible noise generated in the armature or between the armature and the surface of the thrust bearing during operation

  from the engine, to the engine housing, and therefore their propagation

  tion in the engine environment In general, the materials

  the most favorable support rials, such as steel or "Vespel" (registered trademark) are very hard materials, and

  therefore good acoustic conductors, and elastic materials

  ticks that lower noise transmissibility are generally not suitable for use as a support or support The material available under the brand name of "Vespel" is a polyimide resin with graphite charger, manufactured by Du Pont Chemical Corporation, Midland, Michigan, USA Mema adding a coating

  elastic reinforcement, or similar support, to a material

  hard support riau does not necessarily decrease the trans-

  mission of the noise through it, because the abutment load generally brings the elastic material into compression,

  thus increasing its transmissibility of noise.

  In US-A-2,904,709 (Lautner) is

  writes a device for reducing the end play of a shaft for a dynamoelectric machine comprising a rotary armature which comprises an armature shaft supported in rotation

  compared to a stator, and subject to a possible set of ex-

  axial shaft end, the device comprising a body made of an elastic material subjected to thrust forces

  in the axial direction, exerted by the armature shaft.

  The body of elastic material is described as a

  thin nylon disc (registered trademark): this disc is

  tined to act as an elastic thrust bearing which dampens the longitudinal vibrations of the rotor, and reduces noise

during operation.

  The present invention relates to a perfected form

  with a device for reducing the clearance at the end of the armature shaft of a motor, which effectively reduces the

  end play without increased audible noise.

  To this end, a device for reducing the end play of a shaft according to the present invention is characterized in that the body of elastic material comprises a sheet of elastic material having under tension a low transmissibility of noise, the sheet n being supported by the stator only by its adjacent edges

  at one end of the armature shaft and substantially perpetual

  dicular to it, and that a body forming a bearing

  hardened stopper is supported by the sheet of elastic material

  that and is in abutment against said end of the armature shaft so as to tension the sheet of elastic material, in order to reduce the end play of

  the tree, with a low transmission of noise,

  armature bre and of the member forming a thrust bearing towards

the stator.

  A preferred elastic material for this application

  cation is rubber, which is not rigid, while a rigid material such as a nylon disc would transmit a greater amount of noise to the crankcase. The device for reducing the end play of a shaft according to the present invention in fact combines the desirable bearing properties of a hard bearing material with the low transmissibility of noises of an elastic material. In addition, such a device can be manufactured

  from common and inexpensive materials, and be

  appeared quickly and inexpensively, for a production

tion in large series.

  In a particular device according to the present invention, a sheet made of an elastic material having a low transmissibility of noise when it is put

  under tension, like rubber, in particular, is used

  read in combination with a member forming a hardened thrust bearing supported by the sheet in abutment with one end of the armature shaft The sheet is only supported by the motor frame or casing by its edges, and the stopper is supported in the center thereof, so that the axial force from the armature shaft energizes the sheet, for low transmission of noise from the armature shaft and the stopper member to the motor housing or frame. In the drawing: FIG. 1 is an exploded perspective view of a part of an electric motor comprising a preferred embodiment of a device for reducing end play according to the present invention, FIG. 2 is a view from above of a part of the device of FIG. 1 once assembled, and FIG. 3 is an exploded view of the device for reducing the end play according to the present invention

  intended for use in the context of Figure 1.

  Referring to Figure 1 of the drawing, a motor

  electric 10 includes a housing forming a frame, one of which

  tie is shown in 11, which forms part of the stator.

  The casing 11 further supports, by means of radial bearings, not shown, an armature comprising a shaft 12, in one end 13 of which is pressed, or otherwise assembled, an end stop member 14 comprising a grain or ball in one satisfactory hard support material, such as steel or "Vespel" (registered trademark) Many other materials are suitable for the end stop member 14, and those skilled in the art know many ways to spare

  an end stop member in the end 13 of the ar-

bre 12.

  From an end wall 16 of the casing 11 protrudes a housing 17 open towards the end 13 of the armature shaft 12, and which comprises at least one pair of opposite side walls i 8 and, in the present form of

  realization, a bottom wall 19 At least the walls la-

  18, and possibly also the bottom wall 19, have interior surfaces 18 'and 19' which are

  parallel to the axis of the shaft 12 and which have grooves

  ges 20 in communication or circumferentially aligned, Referring to Figure 3, a rectangular flat sheet 22 pn elastic material, having a thickness

  just a little narrower than the width of the grooves 20 pre-

  feels near its center a circular opening 23 A member forming a thrust bearing 25, consisting of a

  hardened support material such as steel or "Vespel" (mar-

  that deposited), has a disc shape, a circular groove

  being organized around it The diameter

  the outside of the stop member 25 is greater than the inside diameter of the opening 23, and the diameter of the bottom of the groove 26 of the stop member 25 is identical

  or less than the inside diameter of the opening 23 Ain-

  if, as shown in FIG. 1, the stop member 25 can

  be arranged in the opening 23 of the sheet 22 of material

  elastic line, making the sheet enter material

  elastic in the groove 26, so that it fits tightly

  As shown in Figures 1 and 2, the sheet 22 of elastic material is inserted into the grooves 20 of the case 17, to be supported 9 e by it only by its edges The skilled person knows many Ways to keep the edges of member 22 in place in the grooves, including deformation of the walls to grip the edges. The end stop member 14 of the shaft 12 bears against an axial surface 27 of the stop member, to put the elastic material 22 slightly under

  tension or shear, so that the play of ex-

  end of the armature shaft 12 is caught up, and its

  axial displacements are eliminated The material

  killing sheet 22 of elastic material, such as rubber

  chouc, is chosen so as to present, under tension or in shear, a low transmissibility of noise, so that the transmission of noise from the armature shaft 12 or the abutment member 25, via the organ 22, towards

  the casing 11, be made minimal The materials of the

  stopper gane 14 and the stopper member 25 are satisfactory complementary support materials, slow wear and low friction Other construction details are not critical to the invention, and are left to the user. appreciation of the skilled person, according to

its particular requirements.

Claims (3)

RESELL ICAT IONS   1 End clearance reduction device   of a shaft for a dynamoelectric machine comprising an in-   rotary duit which comprises an armature shaft supported in rotation with respect to a stator, and subjected to an axial shaft end play, the device comprising a body made of an elastic material subjected to directed thrust forces axially, exerted by the armature shaft, characterized in that the body of elastic material comprises a sheet (22) of elastic material having under tension a low transmissibility of noise, the sheet not being supported by the stator (11 ) only by its edges adjacent to one end of the armature shaft (12)   and substantially perpendicular to it, and that an or-   gane forming hardened thrust bearing (25) is supported by the sheet of elastic material and is in abutment against said end of the armature shaft so as to tension the sheet of elastic material, in order to reduce the play of end of the tree, with low   transmission of noise, armature shaft and gold stop gane towards the stator.   2 device for reducing the end play of a shaft according to claim 1, characterized in that the stator U (1) has a plurality of projecting walls (18, 19) each comprising at least one surface (18 ' , 19 ') parallel to the axis of the armature shaft (12), and having respectively a perpendicular groove (20)   to the axis of the tree, that the sheet (22) of elastic material   tick is only supported by its edges held in place in the respective grooves, and that the stop member (25) has a peripheral groove (26) intended for insertion into a central opening (23) of the sheet in material   elastic, to be held in place by it.   3 End clearance reduction device   of a tree according to one of claims 1 and 2, character-   laughed at by the fact that the sheet (22) of elastic material   consists of a rubber sheet.